Co-cultivation of luminal subtype breast cancer cells with Bifidobacterium animalis enhances the antiproliferative and proapoptotic effect of 2-deoxyglucose

Background: Metabolic reprogramming contributes to breast cancer progression and chemotherapy resistance. Tumor microbiome components can modulate cancer cell metabolism in a strain- and cell type-dependent manner. Bifidobacterium animalis has been shown to enhance glycolysis in breast cancer cells, suggesting that the glycolysis inhibitor 2-deoxyglucose (2-DG) may reduce their survival. Objective: The aim of this study was to evaluate in vitro the combined effect of B. animalis and 2-DG on the viability, proliferation, and apoptosis of breast cancer cells of different molecular subtypes. Methods: The cells lines of human breast cancer of basal (MDA-MB-231) and luminal (T47D, MCF-7) subtypes, and live lyophilized cells of Bifidobacterium animalis subsp. lactis BB-12 were used in the study. Cells were cultivated for 72 h in the absence (control), or presence of bacteria at a cancer cell-to-bacterial cell ratio of 1:400. DG at a concentration of 0.08–50 mM was added to the medium and cells were further incubated for 48 h. Viability was assessed using the trypan blue exclusion test. Apoptosis was analyzed by Annexin V/propidium iodide test, Ki-67 expression was estimated immunohistochemically. Results: It was shown that preincubation of luminal T47D and MCF-7 cells with B. animalis halved the 2-DG IC50 value, caused the maximum accumulation of cells in the late stages of apoptosis and significantly inhibi­ted cells proliferation. Basal MDA-MB-231 cells were found to be most sensitive to 2-DG monotreatment, however, preincubation with Bifidobacterium was followed by a 5.5-fold increase in 2-DG IC50. Conclusions: B. animalis pretreatment altered breast cancer cell sensitivity to the cytotoxic effects of 2-DG in a subtype-dependent manner. In luminal cells, enhanced glycolysis was associated with an increased antiproliferative effect of 2-DG. In contrast, in basal-like MDA-MB-231 cells, co-culture with B. animalis reduced the cytotoxic effect of 2-DG, possibly due to adaptive changes in glucose metabolism or increased metabolic plasticity.